Occasionally notes will cross a page break, so that the page in effect has two page breaks: one within the flow of the main text and one within the note. We encode both page breaks and link them together to indicate that they represent the same break.
Page breaks within notes are encoded with <pb/>. The <pb/> in the note is linked to the corresponding <pb/> in the main text using the id= and corresp= attributes on the two <pb/> elements, to indicate that they are in fact the same page break. The n= attribute is not used on the <pb/> element in the <note>.